Based on my test, the column put in Size bucket can define the bubble size well. From your screenshots, it seems there are too many data in the map. I suggest you to choose Building “PARK HALL” and “MALL CENTER” in the slicer to see if bubble size in the map changes.
You can also check the version of your Power BI Desktop. If it is not the latest version, you can update the latest version of Power BI Desktop(2.59.5135.781 64-bit (June 2018)) and try to show the data again.
If the issue still persists, I would suggest you share pbix file if possible. If the report does contain sensitive data, please upload your report to your OneDrive and send the link to me via private message.
Community Support Team _ Daniel He
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.